1. Field of the Invention
The present invention relates to dimmers, and more particularly, to a method and apparatus for accommodating the dimming of a display and/or lamp regardless of the dimming strategy used by the host motor vehicle.
2. Description of the Related Art
Automobiles and other vehicles are generally provided with electronic indicating panels on dashboards and the like which are controlled by driving circuits. These vehicles are similarly equipped with audio systems which have respective electronic indicators used for tuning, station identification, volume control and similar adjustments by the user.
These electronic indicators have typically been provided with means to adjust the intensity of the vacuum-fluorescent display and/or illuminating lamps, if any, in accordance with the ambient lighting conditions, the running condition of the vehicle and the user preferences. For example, when the vehicle is being operated in areas of high external illumination such as in urban districts, it may desirable to increase the intensity of the illumination of the display and/or illuminating lamps, so that the visibility of instruments may be increased. Similarly, when the vehicle is operated on less frequently traveled routes, it may be desirable to decrease the intensity of illumination of the illuminating lamp or lamps to prevent the distraction or fatigue to the operator or user.
An additional problem with displays and/or illuminating lamps occurs in audio systems which are typically designed without knowing the specific dimming strategy for the host motor vehicle. U.S. Pat. No. 5,339,009 issued to Lai discloses a method and apparatus for distinguishing input signals to generate a common dimming signal. The apparatus converts a signal once it is passed through an optoisolator where it is converted from an analog to a digital signal. Once the signal has been converted, sampling processes are used to determine the common dimming signal required to dim a lamp or series of lamp lines. This disclosure does not, however, disclose a solution to the problem of creating a dimming circuit which can universally receive and accommodate different types of signals and dim a lamp appropriately based on the input signal regardless of the type of signal.